The present invention relates to a hydraulic engine mounting capable of supporting an engine mounted on a vehicle body so as to prevent mechanical interference of the engine with the vehicle body, and prevent transmission of engine vibrations and noises to the vehicle body.
In motor vehicles, most vibration and noise is generated from the engine, and thus are transmitted through a vehicle body to the entire vehicle. Accordingly, it is necessary to minimize the transmission of the vibrations and noises generated from the engine to the vehicle so as to reduce the vibration and noise of the vehicle.
Conventionally, engine mounts are provided with vibration-proof rubber to attenuate the vibration and noise of the engine using the elasticity of the vibration-proof rubber. Recently, a hydraulic mount containing a fluid therein has been developed. In a conventional hydraulic mount a fluid chamber is divided into an upper fluid chamber and a lower fluid chamber by a partition plate. Typically the partition plate is provided with an annular orifice path for fluid communication between the chambers. Also, a plurality of holes are typically formed in a center portion of the partition plate. The holes may be referred to as a decoupler.
When the vehicle travels at a constant speed with engine revolutions in a range of about 1,000 rpm to about 3,500 rpm, the vibration of the engine is in the range of xc2x10.5 to xc2x10.1 mm. This vibration causes the volume of the upper fluid chamber in the conventional hydraulic mount to be changed. The fluid is moved between the upper and lower fluid chambers through the decoupler. The vibration of the engine is thus converted into kinetic energy of the fluid, thereby attenuating the vibration of the engine.
Upon starting or stopping the engine, the vibrating range of the engine is within about xc2x11.0 mm, and at that time, the fluid flows between the upper and lower fluid chambers though not the decoupler but orifice member to attenuate the vibration of the engine. The conventional hydraulic mounting controls the dynamic characteristics through the flow of the fluid, thereby improving performance of reducing the vibrations relative to the engine mounting consisting of the vibration-proof rubber.
However, although the conventional hydraulic engine mount has the superior vibration reducing performance in comparison with the conventional engine mounting consisting of the vibration-proof rubber, it is still limited to the vibration attenuating performance at a low frequency vibration range and a high frequency minute vibration range.
Specifically, since the effect of attenuating the vibration is low at a low frequency range of about 10 to 50 Hz, the shock is easily generated by the vibration upon key on or off. Since it does not control the dynamic characteristic in the high frequency minute vibration range of which a revolution of the engine falls in a range of 3,500 rpm to 6,000 rpm, the vibration frequency falls in the range of 100 to 350 Hz, and an amplitude of the vibration is about xc2x10.05 mm, there is a drawback in that a booming noise can be generated.
Japanese Patent Laid-Open Publication No. Hei 10-19712 discloses an apparatus having a movable partition plate made of rubber, which is deformable by negative pressure of the engine. The movable partition plate is deformed in correspondence with the vibration frequency of the vehicle body detected by a vibration sensor, thereby varying the volume of a fluid chamber and thus attenuating the vibration in accordance with various frequency bands. However, since the apparatus has a vibration sensor for detecting the vibration of the vehicle body and means of negative pressure for deforming the movable partition plate, there is a drawback of complicated and expensive construction.
Accordingly, the present invention is directed to a hydraulic engine mount that substantially obviates one or more problems due to limitations and disadvantages of the related art.
In a preferred embodiment of the present invention, an upper plate is coupled to one vibration source. A lower plate is coupled to a supporting portion, supporting the other vibration source. A body is fixed to an upper portion of the lower plate. The body has an air chamber therein that communicates with the exterior through a plurality of orifices. A variable diaphragm covers an open upper surface of the body. An elastic member is fixed to a lower portion of the upper plate and defines a liquid chamber together with the variable diaphragm. A partition divides the liquid chamber into an upper liquid chamber and a lower liquid chamber which communicate with each other.
Preferably, the diaphragm has a double construction, with a center portion circularly and upwardly extending to contact a bottom of the partition and thus support the partition. The orifices of the air chamber may be arranged at a desired interval along an outer circumference of the body. Preferably, the body is made of polyurethane.
It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the present invention as claimed.